XRCC1 and systemic sclerosis: Particularly, the downregulated genes were categorized into DSB/R (MRE11A, PRKDC; 4- to 9-fold decrease in SSc vs. controls) and base excision repair (PARP1, XRCC1; 4- to 12-fold decrease in SSc vs. controls), and apoptosis-related genes were upregulated (BAX, BBC3; 15- to 18-fold increase in SSc vs. controls) (Figure 3B).